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COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 18 January 2019

Marcin Lefik, Krzysztof Komeza, Ewa Napieralska-Juszczak, Daniel Roger and Piotr Andrzej Napieralski

The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor.

Abstract

Purpose

The purpose of this paper is to present a comparison between reluctance synchronous machine-enabling work at high internal temperature (HT° machine) with laminated and solid rotor.

Design/methodology/approach

To obtain heat sources for the thermal model, calculations of the electromagnetic field were made using the Opera 3D program including effect of rotation and the resulting eddy current losses. To analyse the thermal phenomenon, the 3D coupled thermal-fluid (CFD) model is used.

Findings

The presented results show clearly that laminated construction is much better from a point of view of efficiency and temperature. However, solid construction can be interesting for high speed machines due to their mechanical robustness.

Research limitations/implications

The main problem, despite the use of parallel calculations, is the long calculation time.

Practical implications

The obtained simulation and experimental results show the possibility of building a machine operating at a much higher ambient temperature than it was previously produced for example in the vicinity of the aircraft turbines.

Originality/value

The paper presents the application of fully three-dimensional coupled electromagnetic and thermal analysis of new machine constructions designed for elevated temperature.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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Article
Publication date: 20 September 2018

Daniel Roger and Ewa Napieralska-Juszczak

High-temperature (HT°) motors are made with inorganic coils wound with a ceramic-coated wire. They must be carefully designed because the HT° insulating materials have a…

Abstract

Purpose

High-temperature (HT°) motors are made with inorganic coils wound with a ceramic-coated wire. They must be carefully designed because the HT° insulating materials have a lower breakdown voltages than the polymers used for insulating standard machines.

Design/methodology/approach

The voltage distribution between stator coils is computed with high-frequency (HF) equivalent circuits that consider the magnetic couplings and the stray capacitances. Two time scales are used for getting a fast computation of very short voltage spikes. For the first step, a medium time scale analysis is performed considering a simplified equivalent circuit made without any stray capacitance but with the full PWM pattern and the magnetic couplings. For the second step, a more detailed HF equivalent circuit computes voltage spikes during short critical time windows.

Findings

The computation made during the first step provides the critical time windows and the initial values of the state variables to the second one. The rise and fall time of the electronic switches have a minor influence on the maximum voltage stress. Conversely, the connection cable length and the common-mode capacitances have a large influence.

Research limitations/implications

HF equivalent circuits cannot be used with random windings but only to formed coils that have a deterministic position of turns.

Practical implications

The proposed method can be used designing of HT° machine windings fed by PWM inverter and for improving the coils of standard machine used in aircraft’s low-pressure environments.

Originality/value

The influence of grounding system of the DC link is considered for computing the voltage spikes in the motor windings.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 37 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 November 2016

Ewa Napieralska-Juszczak, Piotr Napieralski, Krzysztof Komeza and Youcef Zeroukhi

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters…

Abstract

Purpose

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters characterizing this type of structures is the uneven distribution of resistivity due to hardening, which is the result of stress exerted on the wires during the manufacturing process.

Design/methodology/approach

The authors have developed a method to take into account the effect of localized hardening on the inhomogeneous distribution of electrical conductivity in the distorted structures of the conductor. To achieve this goal, the authors have implemented a mechanical-electrical simulation method. The resistance characteristics have been measured as a function of mechanical stress.

Findings

As demonstrated by the results of measurements conducted on various samples and with various cable design parameters, the resistance of a given material (copper or aluminum), expressed as a function of stress, does not depend on the type of force applied. Therefore, the same characteristics may be applied to various cable designs.

Practical implications

The method presented in this paper enables more detailed investigation of the influence of particular design parameters on the total resistance of a cable. It also provides the ability to determine optimal settings of design parameters.

Originality/value

The approach is distinct from similar studies because it takes into account the deformed geometry of the conductor and the uneven distribution of the resistivity within a filament. In the literature, it is sometimes stated that the distribution of resistivity in a compacted cable is uneven, but its measurement is deemed impossible. This paper provides a method for determining such a distribution.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 1992

Ewa Napieralska Juszczak and Michał

The paper describes the simulation of a short circuit of one diode in a three‐phase convertor set connected to a 2 winding transformer. The forcing currents are computed…

Abstract

The paper describes the simulation of a short circuit of one diode in a three‐phase convertor set connected to a 2 winding transformer. The forcing currents are computed with the circuit simulation method. The circuit — field model is solved with the finite‐element method. In the paper is presented the distribution of flux lines and values of short circuit forces (strains) solved during one period every 15 degrees in the window of the convertor transformer. This approach to dynamic phenomena using the method presented has not yet been applied to short circuit research in transformers.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 11 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 13 July 2010

Nabil Hihat, Krzysztof Komęza, Ewa Napieralska‐Juszczak, Jean‐Philippe Lecointe and Tadeusz Niewierowicz

The purpose of this paper is to present a comparative analysis concerning the influence of eddy currents on the distribution of the magnetic flux density in the laminated…

Abstract

Purpose

The purpose of this paper is to present a comparative analysis concerning the influence of eddy currents on the distribution of the magnetic flux density in the laminated anisotropic structures.

Design/methodology/approach

The influence of the magnetic flux normal to the lamination surface is particularly analysed. Several models containing internal air gaps and overlapping are tested. For every structure, the eddy currents are first taken into account and then, they are neglected. At last, the 3D simulation of the anisotropic conductivity permits to analyse separately the longitudinal and normal flux in the structure and the eddy currents induced by those fluxes.

Findings

The study leads to a more realistic numerical model with conducting laminations. The results show that the normal flux does not turn at once on lamination. The normal and longitudinal fluxes induce eddy currents which modify the flux distribution in the laminated structure.

Practical implications

The results of the presented simulations make it possible to elaborate a more realistic numerical model of homogenized characteristics taking into account eddy currents.

Originality/value

The eddy currents induced by the fluxes modifies the field distribution in the structure and should be taken into account. The internal air‐gaps higher than 0.1 mm have an influence on the field distribution; the isolation between the laminations of 0.01 mm has a smaller but not negligible effect on the magnetic flux. The direction of the normal flux from one sheet to another one does not change immediately after the entrance of the lamination, the transition is progressive.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 April 1995

Maria Pietruszka and Ewa Napieralska‐Juszczak

The paper presents quasi 3D magnetic field computation for anisotropic layer structure of transformer core, but this computation method can be also applied to other…

Abstract

The paper presents quasi 3D magnetic field computation for anisotropic layer structure of transformer core, but this computation method can be also applied to other magnetically non‐homogeneous structures. To compute magnetic flux density vectors in the layers of the structure the authors applied a new method based on the assumption that different distribution of the magnetic flux in particular layers results from the tendency to reach the minimum of the magnetic field energy.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 14 no. 4
Type: Research Article
ISSN: 0332-1649

Content available
Article
Publication date: 13 July 2010

Ewa Napieralska-Juszczak and Sławomir Wiak

Abstract

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 11 July 2008

Stéphane Duchesne, J‐Ph. Lecointe, F. Périsse and Ewa Napieralska‐Juszczak

This paper aims to propose a high‐frequency (HF) model able to compute the flux density in the vicinity of the laminated stator core of an AC machine.

Abstract

Purpose

This paper aims to propose a high‐frequency (HF) model able to compute the flux density in the vicinity of the laminated stator core of an AC machine.

Design/methodology/approach

Experiments form the main approach. Analytical results previously obtained with a simplified rectangular laminated structure are confirmed with a standard cylindrical magnetic core.

Findings

Three frequency domains are defined, depending on the skin depth relative to the thickness of the magnetic sheets. A methodological approach is proposed for each domain. For higher frequencies, the magnetic core can be considered as transparent for external field computation.

Research limitations/implications

The HF model is valid for skin depths much lower than the thickness of the magnetic sheets.

Practical implications

The proposed HF model provides a link between the weak field measured in the natural void existing between the stator core and the housing of large electrical machines. With such a link, it is possible to develop a new monitoring system able to detect and to localize the partial discharges in the stator winding of a large machine.

Originality/value

The low‐frequency limit of the model has been measured. It corresponds to a ratio of 1/40 between the skin depth and the magnetic sheet thickness. Therefore this model offers a new perspective for maintenance applications.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 13 July 2010

Yoshihiro Kawase, Tadashi Yamaguchi, Tomohiro Umemura, Yoshiyasu Shibayama, Koji Hanaoka, Shingo Makishima and Kazuya Kishida

The purpose of this paper is to clarify the electrical loss of an interior permanent magnet (IPM) motor driven by the pulse‐width modulation (PWM) inverter with various…

Abstract

Purpose

The purpose of this paper is to clarify the electrical loss of an interior permanent magnet (IPM) motor driven by the pulse‐width modulation (PWM) inverter with various carrier frequencies quantitatively.

Design/methodology/approach

An IPM motor driven by the PWM inverter was simulated using the three‐dimensional finite‐element method while changing various carrier frequencies of the PWM inverter. The calculated results are compared with the calculated results differing the number of permanent magnet division.

Findings

The eddy current loss in the permanent magnets decreases as the carrier frequency increases. In the case of low‐carrier frequency, the eddy current loss greatly decreases as the number of permanent magnet division increases. However, the effect of the eddy current loss decreases by the number of permanent magnet division as the carrier frequency increases.

Originality/value

The paper describes the electrical loss of an IPM motor driven by the PWM inverter with various carrier frequencies.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 4
Type: Research Article
ISSN: 0332-1649

Keywords

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